Abstract:Objective:To observe the effect of elevated local sheer stress of abdominal aota on its caliber and wall expression of MMP-9, and analyse the action of high shear stress on arterial remodling.
Methods :Forty-eight SD rats were randomly divided into 4 experiment and 4 comparison groups. An infra-renal aortocaval fistula was constructed by needle puncture using a 0.4mm needle in the experiment groups.The aorta proximal to the fistula was harvested after 1 d, 7 d,14 d and 28 d respectively,while sham operation was done in the comparison groups.The diameter and wall thickness of the aorta were measured after fistula was made and before harvest. The level of change of MMP-9 was observed by immunohistochemistry.
Results:The diameter of aorta proxinal to the fistula was enlarged in the 1d group (P＜0.05),and the values increased with time; but wall thickness was decreased. MMP-9 expression reached the peak value at 7d (P＜0.01),and remained at a high level of expression at 28 d.
Conclusions:Increased shear stress of abdominal aorta in rats can induce positive remodelling with increase in dieameter of arterial wall and decrease in wall thickness, and expression of MMP-9 is upregulated. This positive remodelling is closely related to expression of MMP-9. Increased shear force and increased expression of MMP-9 are important factors in the gradual dilatation of the proximal and distal segments after arteriovenous fistula formation.